The present invention relates to a process for the production of colloidal mortar, particularly for the lining of shaped steel parts such as pipe conduits, and also to the product obtained according to this process.
It is known that the high-colloidal cement-water mixtures suitable for many applications, can also be used as economic substitute for expensive coatings, paints, lacquers, or plastic linings with, for instance, an organic polymer base. One of the main advantages of these mixtures lies in the fact that the shaped steel parts to be coated will not require any previous surface treatment, for instance by sand blasting, which would represent a high factor in calculating production cost for conventional corrosion protection.
A high colloidal cement-water mixture may, for instance, be produced by a process described in the German Patent Application P No. 27 18 236.1, which provides for premixing in a mixer and water, in a proportion of 0.25-0.6, for a period of about two minutes and at a velocity of about 300 m/minute, and then exposing it for at least 8 minutes to a mass acceleration of minimum 2 g (g=9.81 m/sec.sup.2).
Lining mixtures may be produced in this manner, showing, amongst other properties, high adhesion to unprepared steel surfaces. In order to increase the cohesion of the layer finely-cut organic or inorganic fibres may be added to the mixture. The products treated in such a way will have medium pressure and flexural strengths of 850 kp/cm.sup.2 or, respectively, 250 kg/cm.sup.2 (layer thickness 6 mm, curing period 28 days).
It is also known how to use for the outer lining of piping conventional cement-sand-water mixtures with added glass fibers. It is, however, not possible to apply these mixtures to rounded components such as tubes, boilers, or the like, without the aid of bandages. In consequence thereof, however, the economy of the mixture obtained by the adding of sand will become lost by additional, labor-intensive, expense.